Cylindrical breech with sleeved obturator

ABSTRACT

There is herein disclosed an air rifle and/or an air ignition system firearm having a movable breech in the form of a cylindrical plug with an expandable and contractable thin walled obturator jacket to obturate the firing chamber by expansion of the obturator jacket by application of force from high-pressure air and/or propellant gases.

Elited States Patent Jules E. Van Langenhoven La Hulpe, Brussels, Belgium 844,458

July 24, 1969 Dec. 21, 197i Engineering Developments Limited Fribourg, Switzerland Inventor Appl, No Filed Patented Assignee CYLINDRICAL BREECH WITH SLEEVED OBTURATOR 6 Claims, 2 Drawing Figs.

U.S. Cl 42/39.5,

89/7, 89/26 Int. Cl F4lc 13/00 Field of Search 89/1, 7, 24,

[56] References Cited UNITED STATES PATENTS 2,790,353 4/1957 Bird 89/1 .704 3,302,523 2/1967 Van Langenhoven et 89/7 al. 3,354,780 ll/l967 Ramsay 89/26 Primary Examiner-Samuel W. Engle AllomeyHarness, Dickey & Pierce ABSTRACT: There is herein disclosed an air rifle and/or an air ignition system firearm having a movable breech in the form of a cylindrical plug with an expandable and contractable thin walled obturatorjacket to obturate the firing chamber by expansion of the obturator jacket by application of force from high-pressure air and/or propellant gases.

PATENTED 05:21 I97! INVENTOR.

C YLIN DRICAL BREECII WITH SLEEVED OBTURATOR BACKGROUND OF THE INVENTION This invention is related to air rifles and/or air ignition system firearms of the type utilizing caseless ammunition and, more particularly, to air ignition system firearms of the type disclosed in my prior application Ser. No. 473,556 the disclosure of which is specifically incorporated herein by reference.

BRIEF DESCRIPTION OF THE DRAWINGS The inventive principles are illustrated in a presently preferred embodiment as shown in the accompanying schematic drawings in which:

FIG. I is a cross-sectional view of a portion of a gun showing a movable breech in a firing position and FIG. 2 is another cross-sectional view of a portion of a gun showing a movable breech in a loading position.

DETAILED DESCRIPTION A portion of an illustrative air rifle and/or air ignition system gun incorporating the inventive principles is shown to comprise a receiver means 10, a barrel means 12, an air compression cylinder 14, a spring driven air compression piston 16, a piston cushion 17, air passage means 18, valve means 20, and movable breech means 22 between the barrel means 12 and cylinder 14 and providing a firing chamber 24 in which lead pellet or a round of caseless ammunition 26 is held prior to firing the gun. In addition, the gun includes a conventional piston cocking mechanism and a piston releasing trigger-sear mechanism (not shown). The relative sizes of the gun parts are not shown in true perspective, the breech means 22 having been enlarged relative to the other gun parts for purposes of illustration.

The breech means 22 is in the form of cylindrical block 30 slidably mounted in a cylindrical slide chamber 32 for transverse movement relative to the barrel means 12 between a firing position (FIG. 1) and a loading position (FIG. 2). The firing chamber 24 comprises a stepped bore extending parallel to the barrel means with a relatively long rearwardly opening enlarged portion 34 connected to a relatively short barrel connecting bore portion 36 by a shoulder 38. The caseless ammunition 26 includes a metallic projectile portion 40 of lead or the like and a propellant portion 42 ignitable by hot air delivered through passage means 18 from air cylinder 14. The projectile portion is slightly larger than the bore portion 36 so that shoulder 38 provides a shot start and obturation seat for the projectile portion. The length of the firing chamber is greater than the length of the ammunition so that the breech means is movable between the loading position and the firing position with a round of ammunition carried therebetween in the firing chamber. Suitable stop means are provided to locate the movable breech means in the firing position and the loading position. A spring-loaded detent 44 mounted in the receiver means cooperates with a slot 46 in the breech means to limit movement of the breech means to the loading position and to hold the firing chamber and bore in alignment with the barrel means. In the firing position the bottom of the breech means may be seated on the receiver as at 50.

In order to obturate the firing chamber, obturation means are provided in the form of a relatively thin wall expandable and contractable metallic sleeve means 52 of copper, or phosphor bronze or like material, and pressure passage means 54, 56, 58, 60. The thickness of the sleeve wall may be approximately 0.5 millimeters for high pressure applications and approximately 0.1 to 0.2 millimeters for low pressure applications. The sleeve means 52 is mounted on a cylindrical seat 62 of reduced diameter and a transverse shoulder 64. The sleeve means provides an inner pressure applying surface circumjacent the breech means and an outer obturating surface circumjacent slide chamber 32. The cylindrical seat extends beyond and surrounds all sides of the firing chamber and the bore portions 34, 36. The ends 66, 68 of the sleeve means are sealingly fastened on the cylindrical seat as by soldering or the like. Soft lead solder is generally satisfactory for low pressure applications while silver or brass solder is preferred for high pressure applications. Longitudinal passages 54, 56 are located along the central longitudinal axis of the breech means and connect the firing chamber 34 to transverse radially extending passages 58, 60 which terminate in peripheral grooves 70, 72 located between the firing chamber and the sealed ends of the sleeve. The passages 54, 56 intersect the enlarged bore portion 34 a substantial distance from shoulder 38. The relative lengths of the projectile and propellant portions 40, 42 of the round of ammunition are such that the exposed rear end of the lead projectile portion is axially spaced from the intersection of the passages 54, 56 with bore portion 34 toward the shoulder 38 a distance sufficient to prevent lead from being forced into the passages after ignition of the propellant. The grooves 70, 72 and the adjacent space between the inner pressure applying surface and the cylindrical seat 62 provide pressure chamber means in which the high pressure air and/or propellant gases are effective to expand the tin wall sleeve means. The number and location of the passages may be varied as necessary or desirable but particularly satisfactory results have been obtained in a gun having a 4.5 millimeter barrel bore with two centrally located longitudinal passages 54, 56 of 2 millimeter diameter and two transverse passages 58, 60 of l millimeter approximately 0 millimeters, the diameter of the bore portion 36 is 4.6 millimeters while the diameter of the ammunition is approximately 4.75 millimeters. Passages 54, 56 are closed by the threaded plug 74 mounted in a handle portion 76 by which the breech means is manually movable between the loading position and the firing position. It is contemplated that automatic means may be provided to move and to load the breech means.

In operation, to load the gun the breech is moved to the loading position shown in FIG. 2. A lead pellet or a round of ammunition is placed in the firing chamber 34 with the front of the projectile portion 40 seated on the shoulder 38 and the rear of the propellant portion 42 located inside of the outer surface of the breech. Then the breech is moved to the firing position with bore connecting portion 36 aligned with the bore of barrel 12 and firing chamber 34 in communication with air passage 18. After the gun is cocked and ready to be fired, actuation of the trigger releases the piston 16 to compress and heat air in cylinder 14. The compressed and heated air flows through passage 18, past valve 20, and into the firing chamber 34 whereat the propellant is ignited by surface contact therewith and/or the projectile or pellet is driven through bore 12. With a pellet in an air gun, the high pressure air flows through passages 54, 56, 58, 60 to grooves 70, 72 to expand the sleeve and obturate the firing chamber. With a round of ammunition, the burning propellant generates high pressure propellant gases which close the valve 20 and flow through passages 54, 56, 58, 60 to grooves 70, 72. The propellant gases act upon the inner cylindrical surface of the sleeve 52 and cause it to expand into sealing engagement with the wall of chamber 32. While the exact sequence of events with respect to the combined effect of the propellant gases and high pressure air is not presently known, it is a fact that no perceptible amounts of the high pressure air and/or propellant gases escape from the firing chamber. Thus, the high pressure air and/or the propellant gases are more effective in exerting pressure behind the projectile to drive the projectile into the barrel 12 after a predetermined shot start force level is reached in the firing chamber.

I claim:

1. In a gun, a movable breech means movable between a firing position and a loading position,

a firing chamber in said movable breech means, radially expandable and contractable sleeve means mounted on said movable breech means and having an inner cylindrical pressure applying surface and an outer cylindrical obturating surface and being movable radially relative to the breech means between a contracted position during movement of the breech means and an expanded obturating position during firing of the gun, and

passage means connecting said firing chamber to said pressure applying surface of said sleeve means to carry high pressure gas from the firing chamber to the pressure applying surface and radially expand the sleeve means to the obturating position.

2. The invention as defined in claim I and wherein:

said breech means comprising a cylindrical seat extending beyond all sides of said firing chamber, and aid expandable sleeve means being mounted on said cylindrical seat.

3. The invention as defined in claim 2 and wherein said passage means comprises a centrally located passage means extending transversely from said firing chamber within said breech means, and cross passage means extending transversely to said centrally located passage means and opening on said cylindrical seat onto said expandable sleeve means.

4. The invention as defined in claim 3 and wherein said sleeve means being fixed to said breech means beyond said cross passage means.

5. In a gun,

barrel means through which the ammunition is fired,

a source of high pressure high temperature air,

a cylindrical slide chamber located behind said barrel means,

a movable breech means mounted behind said barrel means and being movable between a loading position and a firing position and having a cylindrical portion thereof located in alignment with said barrel means in the firing position and slidably supported within said slide chamber,

a firing chamber in said cylindrical portion of said movable breech means for holding a round of ammunition in a firing position in alignment with said barrel means,

radially expandable cylindrical sleeve means mounted on said movable breech means and being movable therewith between the loading position and the firing position and being movable relative thereto in the firing position between a transfer position substantially abutting said cylindrical portion and an obturating position sealingly engaging said cylindrical side chamber,

there being space circumjacent and between said cylindrical sleeve means and said movable breech means for introduction of high pressure gas providing a sleeve means expanding force, and

passage means connecting said firing chamber to said space to deliver high pressure gas thereto for outwardly expanding said sleeve means to the obturating position.

6. The invention as defined in claim 5 and wherein:

said firing chamber comprising an enlarged diameter bore portion next adjacent said source of air and a reduced diameter bore portion next adjacent said barrel means and a transverse shoulder connecting said enlarged diameter bore portion to said reduced diameter bore portion,

said passage means comprising transverse passage means intersecting said enlarged diameter bore portion at a location axially spaced from said transverse shoulder a distance sufficient to locate the exposed portion of the projectile to be fired from said firearm beyond said transverse passage means toward said barrel means whereby to prevent obstruction of said transverse passage means by the projectile. 

1. In a gun, a movable breech means movable between a firing position and a loading position, a firing chamber in said movable breech means, radially expandable and contractable sleeve means mounted on said movable breech means and having an inner cylindrical pressure applying surface and an outer cylindrical obturating surface and being movable radially relative to the breech means between a contracted position during movement of the breech means and an expanded obturating position during firing of the gun, and passage means connecting said firing chamber to said pressure applying surface of said sleeve means to carry high pressure gas from the firing chamber to the pressure applying surface and radially expand the sleeve means to the obturating position.
 2. The invention as defined in claim 1 and wherein: said breech means comprising a cylindrical seat extending beyond all sides of said firing chamber, and aid expandable sleeve means being mounted on said cylindrical seat.
 3. The invention as defined in claim 2 and wherein said passage means comprises a centrally located passage means extending transversely from said firing chamber within said breech means, and cross passage means extending transversely to said centrally located passage means and opening on said cylindrical seat onto said expandable sleeve means.
 4. The invention as defined in claim 3 and wherein said sleeve means being fixed to said breech means beyond said cross passage means.
 5. In a gun, barrel means through which the ammunition is fired, a source of high pressure high temperature air, a cylindrical slide chamber located behind said barrel means, a movable breech means mounted behind said barrel means and being movable between a loading position and a firing position and having a cylindrical portion thereof located in alignment with said barrel means in the firing position and slidably supported within said slide chamber, a firing chamber in said cylindrical portion of said movable breech means for holding a round of ammunition in a firing position in alignment with said barrel means, radially expandable cylindrical sleeve means mounted on said movable breech means and being movable therewith between the loading position and the firing position and being movable relative thereto in the firing position between a transfer position substantially abutting said cylindrical portion and an obturating position sealingly engaging said cylindrical side chamber, there being space circumjacent and between said cylindrical sleeve means and said movable breech means for introduction of high pressure gas providing a sleeve means expanding force, and passage means connecting said firing chamber to said space to deliver high pressure gas thereto for outwardly expanding said sleeve means to the obturating position.
 6. The invention as defined in claim 5 and wherein: said firing chamber comprising an enlarged diameter bore portion next adjacent said source of air and a reduced diameter bore portion next adjacent said barrel means and a transverse shoulder connecting said enlarged diameter bore portion to said reduced diameter bore portion, said passage means comprising transverse passage means intersecting said enlarged diameTer bore portion at a location axially spaced from said transverse shoulder a distance sufficient to locate the exposed portion of the projectile to be fired from said firearm beyond said transverse passage means toward said barrel means whereby to prevent obstruction of said transverse passage means by the projectile. 